Consumers use tissue products for a wide variety of applications. For example, various types of tissue products may be used, such as facial tissues, bath tissues, paper towels, napkins, wipes, etc. In many instances, various types of liquid-based compositions, such as softening compositions, lotions, friction reducing agents, adhesives, strength agents, etc., are also applied to one or paper webs of the tissue product. For example, a paper web is often softened through the application of a chemical additive (i.e., softener). However, one problem associated with some liquid-based compositions is the relative difficulty in uniformly applying the composition to the paper web of the tissue product Moreover, many application methods are relatively inefficient and thus may result in substantial waste of the composition being applied.
For instance, many softeners are made as an emulsion containing a particular solids content in solution. However, such liquid-based compositions are often difficult to adequately apply to a paper web. In particular, when applying such a liquid-based composition, the paper web can become undesirably saturated, thereby requiring the paper web to be dried. Moreover, it is also difficult to uniformly spread the liquid-based composition on a paper web in such a manner to provide adequate surface area coverage. In addition, some softeners contain components that cause the liquid-based composition to be formed as a solid or semi-solid. To facilitate application of these liquid-based compositions onto a tissue product, extensive heating may be required. Moreover, even after extensive heating, it may nevertheless be difficult to uniformly apply the composition to the tissue surface.
As such, a need currently exists for an improved method of applying a liquid-based composition to a paper web.
In accordance with one embodiment of the present invention, a method of applying a foam composition to a paper web (wet or dry) having a first surface and an opposing second surface is disclosed. The method comprises positioning a foam applicator adjacent to the first surface of the web. The foam applicator defines an extrusion slot through which the foam composition is capable of flowing. In one embodiment, the extrusion slot is in communication with an air channel.
The method also includes flowing the foam composition through the extrusion slot of the foam applicator. Optionally, the flowing foam composition is entrained with an air stream traveling through the air channel. The foam composition is contacted with at least one liquid-permeable partition (e.g., wire-mesh partition, woven or nonwoven fabric, etc.) to fragment gaseous bubbles contained therein before the foam composition is applied to the first surface of the paper web. In one embodiment, the distance from the initial convergence of the foam composition and at least one air stream to the dispensing slot is from about 0.1 inches to about 12 inches, and in some embodiments from about 0.1 inches to about 6 inches. Moreover, if desired, the air channel can converge at an angle of from about 0.5xc2x0 to about 10xc2x0, and in some embodiments, from about 1xc2x0 to about 5xc2x0.
Any number of liquid-permeable partitions may be utilized in the present invention. For instance, in one embodiment, at least two liquid-permeable partitions (e.g., wire-mesh partitions) can be disposed within the air channel so that the one partition is disposed downstream from the other partition. In one particular embodiment, two wire-mesh partitions are utilized that have a different mesh size. For instance, the mesh size of the wire-mesh partition(s) can be less than about 0.1 inches, and in some embodiments, from about 0.03 inches to about 0.08 inches. Moreover, the wire-mesh partition(s) can also define an open area that is less than about 80%, in some embodiments from about 10% to about 70%, and in some embodiments, from about 40% to about 70% of the total area of the wire-mesh partition(s). Further, the wire-mesh partition(s) can also have a mesh count from 1 to 50, and in some embodiments, from 10 to 20 holes in the length direction, width direction, or combinations thereof.
In addition, the method described above can also further comprise positioning a vacuum slot adjacent to the second surface of the web so that the paper web is positioned between the foam applicator and the vacuum slot. Such a vacuum slot can help draw the foam composition onto the first surface of the web. The vacuum slot can also aid in the removal of air from the entrained foam composition.
In accordance with another embodiment of the present invention, a foam applicator system is disclosed for applying a foam composition to a paper web. The system comprises a foam applicator that comprises an extrusion head defining an extrusion slot through which a foam composition is capable of flowing. The extrusion slot is in communication with an air channel through which a stream of air is capable of flowing. The foam applicator includes at least one liquid-permeable partition disposed within the air channel, the liquid-permeable partition being capable of contacting the foam composition.
Other features and aspects of the present invention are described in more detail below.